1. Field of the Invention
The invention relates to an apparatus for mechanically supporting and electrically connecting a magnetic field modulation head to be used for a photomagnetic recording.
2. Description of the Prior Art
It has generally been known in the art that a photomagnetic disc is usable for photomagnetic recording. A conventional apparatus for mechanically supporting and electrically connecting the magnetic field modulation head will be described with reference to FIGS. 1A and 1B. A photomagnetic recording is carried out by contacting a magnetic field modulation head 10 with a surface of a photomagnetic disc 12 at such a contact pressure as to a the magnetic modulation head 10 to be slidable on the surface of the photomagnetic disc 12. The magnetic field modulation head 10 involves a magnetic field modulation coil 10a therein.
The magnetic field modulation head 10 is mechanically supported by a supporting member 20 comprising a metal spring plate which is mechanically fixed to a supporting frame 16. Namely, the magnetic field modulation head 10 is mounted through its mounting portion 20a to one end of the metal spring plate supporting member 20 whose opposite end is fixed to a top portion of the supporting frame 16. The spring plate supporting member has a bent portion which acts as a spring member. The magnetic field modulation head 10 is electrically connected through a conductive plate connecting member 22 for receiving electrical signals for the magnetic field modulation in which the conductive plate connecting member 22 is required to be made of an electrically conductive material to allow the electrical signals to be transmitted therethrough. The conductive plate connecting member 22 is also required to be a flexible member to allow the magnetic field modulation head 10 to exhibit a vertical motion to the surface of the photomagnetic disc 12. The magnetic field modulation head 10 is mounted at its top surface to one end of the conductive plate connecting member 22 whose opposite end is also fixed to the top portion of the supporting frame 16 so that the coil 10a involved in the magnetic field modulation head 10 is electrically connected through a wiring to the conductive plate connecting member 22. The spring plate supporting member 20 and the conductive plate connecting member 22 together constitute a supporting and connecting apparatus.
The supporting frame 16 is L-shaped extends upward and also extends in a lateral direction parallel to but apart from the photomagnetic disc 12. A laser beam pick up device 14 is provided within an end of the laterally extended portion of the supporting frame if, wherein the laser beam pick up device 14 is located at an opposite position to the magnetic field modulation head 10 through photomagnetic disc 12 in which the magnetic modulation coil 10a involved in the magnetic field modulation head 10 is positioned on an optical axis 24 of a lens in the laser beam pick up device 14.
A lift lever 26 may be provided for pushing up a bottom surface of the spring plate supporting member 20 to allow the magnetic field modulation head 10 to be apart from the surface of the photomagnetic disc 12. In detail, the lift lever 26 has a fixed end 26b and a free end 26a with a contact portion. The lift lever 26 is provided at its under surface with a displacement member 28 which is able to show a vertical motion. Upward motion of the displacement member 28 may push up the lift lever 26 so that the contact portion provided at the free end 26a of the lift lever 26 pushes up the bottom surface of the spring plate supporting member 20 until the magnetic field modulation head 10 is separated from the surface of the photomagnetic disc 12. Downward motion of the displacement member 28 stops pushing up the lift lever 26 so that the contact portion provided at the free end 26a of the lift lever 26 may be separated from the bottom surface of the spring plate supporting member 20. This may permit the spring plate supporting member 20 to make the magnetic field modulation head 10 contact with the surface of the photomagnetic disc 12.
The supporting and connecting member 18 comprising the spring plate supporting member 20 and the conductive plate connecting member 22 may be provided to be movable in a diametrical direction of the photomagnetic disc 12 so that the magnetic field modulation head 10 may also be movable in the diametrical direction in contact with the surface of the photomagnetic disc 12 with a rotation for storing information into the photomagnetic disc 12 or the photomagnetic recording.
The conventional supporting and connecting member 18 has, however, problems as described below. The conventional apparatus 18 for mechanically supporting and electrically connecting the magnetic field modulation head 10 has a complicated structure as comprising two separated members consisting of the spring plate supporting member 20 for only mechanically supporting the magnetic field modulation head 10 and the flexible conductive plate connecting member 22 for electrically connecting the magnetic field modulation head 10. A plurality of different fasteners 20a and 22a are necessary to mount the magnetic field modulation head 10 to each of the spring plate supporting member 20 and the conductive plate connecting member 22. In the prior art, the complicated structure of the supporting and connecting apparatus requires a large number of parts as well as complicated fabrication processes. This leads to a costly product.
Moreover, the contact pressure of the magnetic field modulation head 10 on the surface of the photomagnetic disc 12 depends upon not only a spring constant of the spring plate supporting member 20 but also a flexibile of the conductive plate connecting member 22, while the contact pressure must be set just in a predetermined value precisely for realizing the photomagnetic recording. In practice, the problem of the contact pressure of the head 10 on the disc 12 is very serious as it seems difficult to obtain a stable contact pressure value of the magnetic field modulation head 10 due to two associated factors, namely both the spring constant and the flexibility.
Furthermore, the above conventional supporting and connecting apparatus has a further serious problem with the accuracy of the positioning of the magnetic field modulation head 10. Cooperation of the spring plate supporting member 20 with the conductive plate connecting member 22 may cause a variation of a distance L of the magnetic field modulation head 10 from the vertical portion of the supporting frame 16. This results in difficulties in precisely positioning the magnetic field modulation head 10 on the photomagnetic disc 12. This problem as to the variation of the positioning of the magnetic field modulation head 10 is also very serious as it seems difficult to obtain a stable and precise positioning thereof.
To solve the above problems, it is therefore necessary to develop a novel apparatus for mechanically supporting and electrically connecting the magnetic field modulation head 10.